New oxynitrides of RZrO2N (R = Pr, Nd, and Sm) have been synthesized via a direct solid-state reaction of R2O3 with Zr2ON2 at 1200-1500 degrees C under 2-3 GPa pressure. Powder X-ray diffraction shows that all three phases adopt an orthorhombic Pnma perovskite superstructure [a = 5.8537(1) angstrom, b = 8 1707(1) angstrom, and c = 5.7093(1) angstrom for NdZrO2N] and the structural distortion increases with decreasing R3+ ionic radius. This method may enable new mixed-metal oxynitrides to be synthesized without the use of nitriding gas atmospheres.